What can happen in certain states, is that repeat offenders are hit with escalating prison terms each time they are convicted (the classic example are the three-strikes-your-out laws), whereby someone can be sentenced to a life term.
In those cases, sentences don't translate to actual prison terms since non-violent offenders are routinely paroled.
There's still a lot of heavy handedness, and I question the justice of escalating sentencing, but the comments above create a false impression of the US justice system.